The study's purpose is to investigate the relationship between treatment variables and rehabilitation outcome in heroin addicts in a manner that allows the identification of the causal links between treatment and rehabilitation. Clients are randomly assigned to either the experimental condition (Interpersonal Problem Solving Skills Training Program), the attention control group, or the no treatment control group. Comparisons will be made between the experimental and control conditions using the rehabilitation change variables under study which include both traditional outcome measures and indices of intermediate changes in attitudes, values and self concept. The project will also develop and pilot a vocational skills training package for use in methadone clinics. This vocational program will provide a problem solving orientation to seeking and maintaining employment.